VIDEO: Experiment with a potato
Carry out the potato experiment yourself - it's child's play
- Cut the potatoes or open the substitute fruit with the knife.
- Put some salt on the cut surface.
- After a short time, a film of liquid has formed on the cut surface of the potato.
By the way, this method is used by clever housewives to soften the bitter taste of cucumbers, eggplants to add excess liquid and also to preserve meat or fish (salt drying). And fruits such as strawberries also tend to form juice when you use them sugars.
Why does salt dehydrate the fruit?
In fact, it is a bit astonishing that potatoes can be "milked" more or less voluntarily under the influence of salt. he physical term for this process is called "osmosis".
Salt draws water out? - biological knowledge
Surely you know the effect that if you have eaten very spicy, sweet or salty ...
- Osmosis is based on the endeavor of natural processes to balance each other out. This applies, for example, to temperatures, but also to the concentrations in solutions.
- So salt solutions and water - if you allow it - will mix until the entire solution has a uniform concentration. Incidentally, this process is called diffusion.
- But what happens if this is obstructed by a membrane (for example the cell walls of the potato) in such a way that the water can pass through, but the larger salt molecules cannot? As happened in the experiment, a kind of impeded compensation will also take place in this case: The water exits the cells and ensures that the salt concentration on the outside decreases.
- However, the salt cannot get in through the cell membranes of the fruit. Overall, only the cell fluid moves in the direction of the stronger solution.
By the way: The experiment shown has another interesting variant. Put potato pieces in salt solutions of varying strength and watch what happens. The potatoes will shrink the most in the solution with the most salt.
